1. Field of the Invention
This invention is directed to data storage devices, or disk drives, of the type that receive a removable disk cartridge. More specifically, the present invention is directed to a method for permanently write-protecting data on a data storage medium after the data has been transferred to the storage medium.
2. Brief Description of Prior Developments
Removable disk cartridges for storing digital electronic information typically comprise an outer casing or shell that houses a rotatable storage medium, or disk, upon which electronic information can be stored. The cartridge shell often comprises upper and lower halves that are joined together to house the disk. The disk is mounted on a hub that rotates freely within the cartridge. When the cartridge is inserted into a disk drive, a spindle motor in the drive engages with the disk hub in order to rotate the disk within the cartridge. The outer shell of the cartridge typically has some form of opening near its forward edge to provide the read/write heads of the drive with access to the recording surfaces of the disk. A shutter or door mechanism is often provided to cover the opening when the cartridge is not in use to prevent dust or other contaminants from entering the cartridge and settling on the recording surface of the disk.
Presently, disk cartridges are provided with some form of write protection. For example, conventional 3.5xe2x80x3 floppy disks have a mechanical slider mounted in a corner of the cartridge housing that can be moved from one position to another to indicate whether the floppy disk is, or is not, write-protected. An optical or mechanical switch in a floppy disk drive detects the position of the mechanical slider on the cartridge to determine whether the cartridge is write-protected. If so, the disk drive inhibits writing of information to the storage medium within the floppy disk cartridge. Unfortunately, the mechanical slider on the disk cartridge and the associated mechanical or optical switches in the disk drive increase the costs of the cartridge and drive. Moreover, there is no way to prevent a user from changing the write-protect status of the cartridge. All a user has to do is change the position of the mechanical slider, either intentionally or unintentionally, and valuable data may be destroyed.
Disk cartridges can also be read/write protected electronically as disclosed in U.S. Pat. No. 5,644,444 to Braithwaite et al. Braithwaite et al. discloses writing protection modes in predetermined locations on the storage medium that can be password protected. Nevertheless, the protection modes can still be changed, thus allowing for the opportunity of either unwanted or unauthorized changes to be made to the data on the disk.
Where it is desirable to prevent data contained on the cartridge from being altered, the above-described mechanisms fall short in that they allow the cartridge protection mode to change at will between protected and unprotected modes. Hence, even after write protecting a cartridge to prevent writing to a cartridge, a user desiring to alter the data must simply change the protection mode back to an unprotected mode.
Common VHS video cartridges provide a mechanism for permanently write protecting the video information that they bear via a mechanical write protect tab. By removing the tab, the video cartridge will not accept further recording. However, such mechanical solutions can be defeated. For example, video cartridges overwrite protection mechanism can be easily defeated by replacing the tab with tape or the like.
Thus, there is a need for an electronic overwrite protection method for the storage medium of a disk cartridge.
The present invention addresses the above need by providing method and apparatus for permanently providing electronic overwrite protection for a disk cartridge. The cartridge comprises a rotating storage medium that comprises tracks that are not accessible to a host device. The storage medium further comprises a write-secure-complete indicator that is located on a portion of the storage medium not accessible to the host device. A user of the host device that desires to protect the data contained on the storage medium commands a storage device containing the disk cartridge to set the write-secure-complete indicator. Thereafter, the storage device permanently set the write-secure-complete indicator.
Furthermore, the cartridge comprises a write-secure type media indicator that identifies the cartridge as being susceptible to write secure protection. According to an aspect of the invention, the storage device will only allow cartridges designated a write-secure type (via the indicator) to be permanently overwrite protected.
The write-secure type indicator comprises a predefined location of the storage medium. According to one embodiment, the write-secure type indicator comprises a predefined location on a track on the medium, preferably on a track not accessible by the host device. According to an alternative embodiment, the write secure indicator comprise an indelible mark that is formed in the magnetic coating of the medium.